Before I answer this question I just want you to know that there's probably a more elegant way of doing whatever it is you're trying to do. This dialplan snippet is pretty short. My first question would be: how does a call get to this point? Also, what is the big picture, that is, what's the application you're creating? Remember the golden rule: Anything that you do in Asterisk is easier to do in FreeSWITCH, but you need to learn the ropes a bit.

The answer to your question is, of course, "It depends." :P Give us the background on what you're doing so that we can give you an educated answer. You could use the <condition> tags with actions and anti-actions. You could also call a Lua/JavaScript/Perl/Python/etc. script to handle the logic but that's probably overkill.

Tell us more and we'll tell you more. ;)

Thanks!
-Michael Collins